A few key resources for Earth Day and in the future:

(1)  Mapping the Environment:  10 resources:

http://blogs.esri.com/esri/gisedcom/2013/10/18/mapping-the-environment/

(2)  Spatial Environmental Education – article with ideas on curricular implementation of field work, mapping, analysis:

http://www.earthzine.org/2012/09/24/spatial-environmental-education-teaching-and-learning-about-the-environment-with-a-spatial-framework/

(3)  The importance of outdoor education – my video:

http://www.youtube.com/watch?v=66RyCZOe0ao&feature=player_embedded

(4)  Advancing STEM education with GIS:

http://www.esri.com/library/ebooks/advancing-stem-education-with-gis.pdf